ST10R272 View Datasheet(PDF) - STMicroelectronics

Part Name

Description

Manufacturer

ST10R272

16-BIT LOW VOLTAGE ROMLESS MCU WITH MAC

STMicroelectronics 

ST10R272L - WATCHDOG TIMER

SSPCKS Value

Synchronous baud rate

011

SSP clock = CPU clock divided by 16

3.13 MBit/s

100

SSP clock = CPU clock divided by 32

1.56 MBit/s

101

SSP clock = CPU clock divided by 64

781 KBit/s

110

SSP clock = CPU clock divided by 128 391 KBit/s

111

SSP clock = CPU clock divided by 256 195 KBit/s

Table 11 Synchronous baud rate and SSPCKS reload values

12 WATCHDOG TIMER

The Watchdog Timer is a fail-safe mechanism which limits the malfunction time of the

controller. The Watchdog Timer is always enabled after device reset and can only be disabled

in the time interval until the EINIT (end of initialization) instruction has been executed. In this

way, the chip’s start-up procedure is always monitored. The software must be designed to

service the Watchdog Timer before it overflows. If, due to hardware or software related

failures, the software fails to maintain the Watchdog Timer, it will overflow generating an

internal hardware reset and pulling the RSTOUT pin low to reset external hardware

components.

The Watchdog Timer is a 16-bit timer, clocked with the system clock divided either by 2 or by

128. The high byte of the Watchdog Timer register can be set to a pre-specified reload value

(stored in WDTREL) in order to allow further variation of the monitored time interval. Each

time it is serviced by the application software, the high byte of the Watchdog Timer is

reloaded. The table below shows the watchdog time range which for a 50MHz CPU clock

rounded to 3 significant figures.

Reload value

in WDTREL

FFH

00H

Prescaler for fCPU

2 (WDTIN = ‘0’)

10.24 µs

2.62 ms

128 (WDTIN = ‘1’)

655 µs

168 ms

Table 12 Watchdog timer range

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